Stepper motors which cause a certain amount of motion in response to a an input electrical pulse are well known to those skilled in the art. They are disclose, for example, in P. C. Sen's "Principles of Electric Machines and Power Electronics" (John Wiley and Sons, New York, 1989). The stepper motors disclosed in the Sen book have contacts between stationary and moving parts and, thus, lose a substantial amount of energy to friction.
A superconducting stepper motor is described in an article by Andrew A. Moultrhop et al. entitled "Superconducting stepper motors," Rev. Sci. Instrum. 59 (4), April, 1988. The motor described in this paper is rotary, and it contains a several coils, each of which have many windings. This motor is not capable of moving an object in planar motion.
A linear motor with superconductive elements is disclosed in Japanese patent number 63-262056. The motor of this patent contains large stator coils, which necessitates a relatively large size for the motor and limits its usefulness in applications requiring small stepper motors.
Another linear motor with superconductive elements is disclosed in Japanese patent number 1034171. The motor of this patent also contains large coils, necessitates a large size, and limits its usefulness in applications requiring smaller size.
Superconducting tooth structures for electromagnetic devices are described in IBM Technical Disclosure Bulletin Vol. 31 No. 9 (February, 1989). The apparatus of this invention does not appear to be able to readily move an object in two- or three-dimensions within a relatively small space.
It is an object of this invention to provide a contactlass stepper motor which is substantially more efficient than most of the prior art stepper motors.
It is another object of this invention to provide a small, contactless stepper motor which has a maximum dimension of less than 10 centimeters and which is able to move a magnetized object in two- or three-dimensions within a relatively small space.